Overcurrent release of electric switch in particular of switch breaker

ABSTRACT

A circuit breaker provided with a thermal and electromagnetic element has two levers and two torsion springs. The torsion springs are prestressed and exert on the levers oppositelydirected forces, whereby the force exerted by the first torsion spring on the first lever is greater than the force exerted by the second torsion spring on the second lever. The levers act as the force-transmitting members of the breaker.

United States Patent ['19] Kubiak et al.

OVERCURRENT RELEASE or ELECTRIC SWITCH IN PARTICULAR or SWITCH BREAKERInventors: Tadeusz Kubiak; Jan Jagiello, both of Lodz, Poland LodzkieZaklady Aparatury Elektrycznej, Lodz, Poland Filed: Apr. 23, 1971 Appl.No.: 136,749

Assignee:

Foreign Application Priority Data Apr. 30, 1970 Poland 140335 US. Cl337/71, 337/7, 337/48 Int. Cl. H0lh 71/16 Field of Search 337/7, 48, 50,55,

References Cited UNITED STATES PATENTS 10/1967 Gauthier 337/48 PrimaryExaminer-Bernard A. Gilheany Assistant Examiner-A. T. GrimleyAttorney-Karl F. Ross [57] ABSTRACT A circuit breaker provided with athermal and electromagnetic element has two levers and two torsionsprings. The torsion springs are prestressed and exert on the leversoppositely-directed forces, whereby the force exerted bythe firsttorsion spring on the first lever is greater than the force exerted bythe second torsion spring on the second lever. The levers act as theforce-transmitting members of the breaker.

3 Claims, 3 Drawing Figures l 4 l3 3' H Patented Sept. 25, 19733,761,854

3 Sheets-Sheet 1.

F IG] TADEUSZ KU'BIAK JAN JAGI EH50 INVENTORQ 3 "ff-: BY 5' (h 24;."

ATTORNEY Patented Sept. 25, 1973 3,761,854

3 Sheets-5heet 2 FIG. 2

TADEUSZ KUBIAK JAN JAGI BRO INVE BY (1 FL U ATTORNEY Patented Sept. 25,1973 3,761,854

3 Sheets-Sheet 5 FIG. 3

TADEUSZ KUBIAK JAN JAGI EE'LO LL BY au a ATTORNEY OVERCURRENT RELEASE OFELECTRIC SWITCH IN PARTICULAR OF SWITCH BREAKER Field of the InventionThe invention relates to the overcurrent release of an electric switchand more particularly, to a switch breaker.

BACKGROUND OF THE INVENTION The release devices of low-voltage circuitbreakers have a thermal element, electromagnetic element, and amechanism with a shaft in which a lever is rotatably mounted togetherwith a torsion spring. The lever is provided with a long and a shortarm, the latter carrying a roller.

When the circuit breaker is open circuited, the torsion spring holds thelong arm of the lever away from a boss on a movable rod. During settingof the circuit breaker, a tooth of a lock-releasing lever presses theroller mounted in the short am of the lever with great force and rotatesits lever in the direction opposite the bias of the torsion spring.

A drawback of this release device consists in that, the lock releasinglever, when disengaging, must overcome the force exerted by the torsionspring in order to shift the roller. This delays the disconnection ofthe circuit breaker.

OBJECT OF THE INVENTION The object of the invention is the developmentof such a circuit-breaker release mechanism which is capable ofshortening the operating time of the circuit breaker and enablescalibration of its mechanism without other parts of the circuit breaker.

SUMMARY OF THE INVENTION This object has been achieved in a mechanism inwhich the support is provided with a common shaft on which two leversand two torsion springs are rotatably mounted. The springs are arrangedso that they are tensioned and exert oppositely directed forces on thesetwo levers.

The force exerted by the first torsion spring on the first lever isgreater than the force exerted by the second torsion spring on thesecond lever.

The two levers are so situated and shaped that a long arm of the firstlever rests on the boss of a movable rod, and the short arm of thislever has a length such that it is situated in the path of thecircuit-breaker handle.

The second lever has a lug on its long arm, which is in the path of thelong arm of the first lever. On the short arm of the second lever thereis provided a roller which blocks the tooth of the lever adapted to tripthe lock of the circuit breaker.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. I is a cross-section (taken along line l I of FIG. 3) of therelease mechanism;

FIG. 2 is a view of the release mechanism from the side (arrow ll ofFIG. 1); and

FIG. 3 is a sectional view (along Line III III of FIG. I) of themechanism.

SPECIFIC DESCRIPTION The switch or circuit breaker of the presentinvention comprises an insulating body (FIGS.1 3) which extends over thelength of the housing 1' (FIGS.1 and 3) to which it is secured by screws1" (FIGS! and 3).

Screws 2 (FIGSJ and 2) attach a support 3 from below to the insulatingbody 1, the support 3 having a pair ofdownwardly extending legs 3'(FIGS.1 and 2) in which a shaft 4 (FIGS.] and 2) is mounted.

The shaft 4 carries two bent levers 5, 6 through which the shaft passesand which are independently rotatable on the shaft 4 as best seen inFIGSJ and 2. A pair of torsion springs 7 and 8, likewise mounted on theshaft 4, have legs engageable with the levers 5 and 6, respectively, andother legs received in holes of the support 3 as will be apparenthereinafter so that a torque is applied by each spring to the respectivelever.

The leg 9 (FIGS.! and 2) of spring 7, for example, engages in a hole 11of the support 3 (FIG.1) while the other leg 13 of the torsion spring 7engages an arm 14 of the first lever 5, partly broken away in FIG.2.

A leg 10 (FIG.2) of the second spring 8 is received in a hole 12 of thesupport 3 while another leg 15 (FIG.2) rests on the short arm 28 of thesecond lever 6.

The torsion springs 7 and 8 are prestressed and exert counterdirectedforces (about the shaft 4 as seen in I FIG.l) on the levers 5 and 6 suchthat the force applied by the torsion spring 7 to the first lever 5 isgreater than the force applied by the torsion spring 8 to the secondlever 6.

The first lever 5 has a long arm (FIGSJ and 2) which is provided at itsfree end (FIG.l with an arcuate portion 18 corresponding to the arc of acircle with a radius drawn from the axis of rotation of this lever, i.e.the axis of shaft 4. The lever arm 17 is provided with an undercut l9(FIG.l) limited by a segment which is tangential to the circledescribing a boss 20 or pin (FIGSJ and 2) ofa movable trip bar 21 duringits rotation.

The trip bar 21 (see especially FIGSJ and 3) is mounted by pivotarrangements 47' in a pair of trunnions rising from the plate 1 and bestseen in FIG.3. Thus the trip bar 21 can swing about an axis parallel tothe shaft 4 and perpendicular to the plane of the paper in FIG.1.

The short arm 22 of lever 5 (best seen in FIG.1) has a length such thatit lies in the path along which a member 23 of a handle 24 of thecircuit breaker is movable (FIGJ). The circuit breaker handle has beenremoved to reveal the overlying structure as viewed in FIG.2. The secondlever 6 (FIGSJ and 2) has a long arm 25 on which is provided a lug 26(FIG.1) in the path of the long arm 17 of lever 5 and is formed with anabutment 27 (FIG.1).

The lever 6 is also provided with a short arm 28 (FIGS.1 and 2) in whicha roller 29 is fixed. The roller 29 holds down a tooth 30 (FIG!) oflever 31, the latter forming a switch latch that releases the lock ofthe circuit breaker (see FIG.1).

On the other side of the insulating body 1 (i.e. above the body 1 thereare provided three thermal and electromagnetic elements (FIG.3). Thethermal elements consist of thermal metal (bimetallic) strips 32 (FIG.1a heater 33 (FIGSJ and 2) and an insulating pad 34 between two arms ofthe heater 33 and together with thermal metal strips 32 are permanentlyfixed to a frame 35 (FIGSJ and 3) by means of rivets 36 and rectangularpads 37 (FIGJ).

The bent arm 38 (FlG.1) of frame 35 carries a pilot sleeve 39 (FIGSJ and3) at the end of which a pin 40 is mounted. The armature 41 of theelectromagnetic element is provided at the end of pin 40. The armature41 rests upon the bent arm 38 of frame 34 and is held in place by a coilspring 42 and a nut 43 threaded onto the threaded part of pin 40 (FIGSJand 3). A nut 44 is also provided on this pin 40. The armature of theelectromagnetic element is designed to act upon the trip bar 21 whileexerting a pressure on the arm 45 of the rod (FIGJ). Frame 35 and core46 of the electromagnetic elements (FIGSJ and 3) are attached to theinsulating body 1 via the screws 2 mentioned earlier (FIGSJ and 2).

A spring 48 (F161) is provided between the body 1 and the trip bar 21 toprovide the restoring force when the latter is shifted. The trip bar 21(FIGSJ and 3) also is provided with a long bolt 49 and three short bolts50, the long bolt 49 being used to position the movable rod with respectto the trip bar 21 (FIG.3). The short bolts 50 are used to establishequal distances between bimetallic elements 32 and the closest part ofthe trip bar 21. Bolts 49 and 50 are provided with locking nuts 51 and52 to retain them after they have been set.

The shaft 4 is held between the legs 3' of the support 3 by means ofsplit rings 16 (F162).

When the handle 24 of the circuit breaker (FlG.1) is shifted into itslower extreme position, the lever 23 of this handle rotates the shortarm 22 of lever 5 until the long arm 17 of this lever is engaged by pin20 of the trip bar 21 (FIGS.] and 2). This motion stresses the torsionspring 7 and rotates the second lever 6 in the same sense. When member26 of lever 6 (rotating in the clockwise sense in FIG.1 engages thesupport 3, the roller 29 on this lever 6 assumes a position blocking thetooth 30 of lever 31 and preparing for release of the latch. Now, whenthe handle 24 is returned to its upper extreme position, the circuitbreaker is switched on. Should any disturbance in the power networkarise, the thermal or electromagnetic means rotate the trip bar 21 andwithdraw the pin 20 from engagement with arm 17. The torsion spring 7then swings this arm in the opposite sense to its original displacementuntil the second lever 6 is entrained and the circuit breaker released.The roller 29 is withdrawn from the path of the tooth 30 and the lever31 is therefore permitted to rotate to release the lock. The circuitbreaker connections are interrupted.

We claim:

1. A circuit breaker release mechanism comprising: a support;

a shaft mounted on said support,

a first lever and a second lever journaled for rotation on said shaft,each of said levers having a pair of arms;

first and second torsion springs acting upon said first and said secondlever respectively in opposite senses and with a greater force on saidfirst lever than the force on said second lever;

a rod mounted on said support for at least limited angular displacementabout an axis, said rod being operatively connected to circuit-breakingmeans for opening and closing a circuit in accordance with the positionof said rod; and

a breaker resetting handle mounted on said support, one arm of saidfirst lever engaging said rod and the other arm of said first leverlying in the path of said handle, one arm of said second lever lying onthe path of said one arm of said first lever and the other arm of saidsecond lever being provided with a roller cooperating with a switchlatch of the breaker whereby said first spring is stressed uponactuation of said handle to bias said first lever against said rod anddisengagement of said rod from said first lever effects displacement ofsaid second lever to release said switch latch.

2. The mechanism defined in claim 1 wherein said one arm of said secondlever is formed with a boss adapted to rest upon an abutment of saidsupport, said latch including a latching lever controlled by said rollerand having a tooth deflected thereby, said boss being so constructed andarranged that a straight line passes through the axis of said roller andthe axis of said shaft when said boss engages said abutment andsubstantially coincides with the force-action line of said tooth uponsaid roller.

3. The mechanism defined in claim 1 wherein said one arm of said firstlever is provided with an arcuate extremity having a center of curvatureat the axis of said shaft and a notch formed with a segment tangentialto the arcuate path of a portion of said rod engageable by said firstlever.

1. A circuit breaker release mechanism comprising: a support; a shaftmounted on said support, a first lever and a second lever journaled forrotation on said shaft, each of said levers having a pair of arms; firstand second torsion springs acting upon said first and said second leverrespectively in opposite senses and with a greater force on said firstlever than the force on said second lever; a rod mounted on said supportfor at least limited angular displacement about an axis, said rod beingoperatively connected to circuit-breaking means for opening and closinga circuit in accordance with the position of said rod; and a breakerresetting handle mounted on said support, one arm of said first leverengaging said rod and the other arm of said first lever lying in thepath of said handle, one arm of said second lever lying on the path ofsaid one arm of said first lever and the other arm of said second leverbeing provided with a roller cooperating with a switch latch of thebreaker whereby said first spring is stressed upon actuation of saidhandle to bias said first lever against said rod and disengagement ofsaid rod from said first lever effects displacement of said second leverto release said switch latch.
 2. The mechanism defined in claim 1wherein said one arm of said second lever is formed with a boss adaptedto rest upon an abutment of said support, said latch including alatching lever controlled by said roller and having a tooth deflectedthereby, said boss being so constructed and arranged that a straightline passes through the axis of said roller and the axis of said shaftwhen said boss engages said abutment and substantially coincides withthe force-action line of said tooth upon said roller.
 3. The mechanismdefined in claim 1 wherein said one arm of said first lever is providedwith an arcuate extremity having a center of curvature at the axis ofsaid shaft and a notch formed with a segment tangential to the arcuatepath of a portion of said rod engageable by said first lever.